1. Field of the Invention
The present invention relates generally to containers that include an internal module that adds heat to or removes heat from a material, such as a food, beverage, medicine, or the like, in the surrounding container.
2. Description of the Related Art
Containers may have integral modules for warming materials in the container, such as sake, coffee, or soup. Examples of such self-heating containers are disclosed in U.S. Pat. Nos. 5,461,867; 5,626,022; and 6,351,953 issued to Scudder et al. All patents, patent applications and other publications referenced in this application are hereby incorporated by reference herein in their entirety. Such containers typically include an outer can or body, in which the food or beverage is sealed, and an inner can or thermic module that contains two chemical reactants that are stable when separated from one another but, when they mix in response to actuation of the thermic module by a user, produce an exothermic reaction or, alternatively, an endothermic reaction and thereby heat or cool the contents of the container.
As part of the manufacturing process of such containers which are used for holding food and beverages, the containers must go through a sterilization process called “retort.” In general the retort process consists of subjecting the container and food contents to high temperatures and pressures. In a typical retort process, the container and contents are placed in a chamber for several minutes at 252 degrees Fahrenheit and two bars of pressure. Accordingly, the containers must be designed to withstand the retort process and still function properly.
The heating or cooling module (thermic module) is typically attached at one end of the cylindrical container body, and the elongated cylindrical reaction chamber portion of the module extends into the container body. This elongated portion functions as both a chamber in which to contain the reaction and a heat-exchanger for transferring heat between it and the surrounding contents of the container body. The thermic module has two chambers, each of which contains one of the chemical reactants, separated by a breakable barrier such as metal foil or a thin plastic film. Typically, one of the reactants is a liquid, and the other is in a solid powdered or granular form. Calcium oxide (commonly known as limestone) and water are examples of two reactants known to produce an exothermic reaction to heat the contents in such containers. Other combinations of reactants are known to produce endothermic reactions to cool the container contents. A cap containing the liquid reactant is disposed in the end of the thermic module attached to the container body. At one end of the cap is an actuator button that a user may press to initiate the heating or cooling. The barrier seals the other end of the cap. The cap has a pushrod or similar prong-like member that extends from the actuator button nearly to the barrier. Depressing the actuator button forces the prong into the barrier, puncturing it and thereby allowing the liquid reactant to flow into the solid reactant in the reaction chamber. The heat produced by the resulting exothermic reaction or absorbed by the resulting endothermic reaction is transferred between the reaction chamber of the thermic module and the contents of the container body by conduction. Exothermic reactions also typically generate a gas and/or steam, which is allowed to escape through vents in the end of the container. The user inverts the container and, when the contents have reached the desired temperature, consumes the contents. The second end of the container body has a seal or closure, such as a conventional beverage can pull-tab, that may be opened and through which the user may consume the heated or cooled contents.
These elongated containers having elongated, cylindrical thermic modules and container bodies are best suited for heating or cooling liquid materials such as drinks, soups or other less viscous food products. The elongated containers are not as useful for solid, semi-solid or viscous food products, such as stew, chili, chicken, beef or the like. This is true for several reasons. First of all, the elongated container body is similar to a typical drinking container like a drinking glass or cup where the contents are consumed by drinking directly out of the container. The relatively small top surface of the elongated container body limits the size of the opening that can be provided for consuming out the contents of the container. This is fine for drinking or pouring directly out of the container, but when eating with a utensil such as a fork, spoon and/or knife, it is undesirable.
In addition, the heating of cooling of a liquid or low viscosity food product creates natural convection to distribute the heat from the heat source (cooling from the cold source, as the case may be) throughout the contents of the container. Moreover, minor movements or shaking of the container mixes the liquid further distributing the heat. With solid or more viscous contents, the heat from the heat source is non-uniformly applied to the food contents nearest the interface of the thermic module and the container body and heat is distributed mainly by conduction.
Accordingly, the present invention is directed to improvements in self-heating and self-cooling containers for solid, semi-solid or viscous food products which overcome these problems and deficiencies of previous containers.